Alternating-current electromagnetic switch.



A. SUNDH. ALTERNATING CURRENT ELEGTBOMAGNETIO SWITCH.

APPLIOATION IILBD NOV. 22, 1907.

1,105,31 1 Patented July 28, 1914.

4 SHEETS-SHEET 1.

f "mu A W A. SUNDH.

ALTERNATING CURRENT ELECTROMAGNETIC SWITCH.

APPLICATION FILED NOV. 22, 1907.

1,1 05,3 1 1 Patented July 28, 1911 4 SHEETS-SHEET 2. fig. 3.

A. SUNDH. ALTEBNATING CURRENT ELECTROMAGNETIC SWITCH.

APPLICATION FILED NOV.22, 1907. 1,1 05,31 1 Patented July 28,1914.

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WITNESSES:

Wamva INVENTZfiM W ATTORNEY A. SUNDH. ALTERNATING CURRENT ELECTROMAGNETIC SWITCH. APPLICATION FILED NOV. 22, 1907.

1, 1 05,31 1 Patented July 28,191&

4 SHEETS-SHEET 4.

fl me a2; M. W

ATTORNEY UNITED 'STATESHPATENT OFFICE.

AUGUST SU'NDH, OF YONKERS, NEW YORK, ASSIGNOR TO OTIS ELEVATOR COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF NEW JERSEY.

ALTERNATINGC'URRE'NT ELECTROMAGNETIC SWITCH.

Specification of Letters Patent.

Patented July 28, 1914.

Application fled November 22, 1907. Serial No. 403,276.

To all whom it may concern: Be it known that I, AUGUST SUNDH, a citizen of the United States, residing at Yonkers, in the county of VVestchester and State of New York, have invented new and useful Improvements in Alternatin -Current Electromagnetic Switches, of whic the fol-' lowing is a specification.

My invention relates to electromagnetic Switches per circuit-closers particularly adapted for use in connectionwith alternating or intermittent currents;

One of the objects of the invention is the provision of a construction in which the chattering due to a pulsating current us greatly minimized, in which the switch and its magnet are substantially silent in opera tion, and in which the electro-magnet is efficient and reliable in operation.

Other objects of my invention will appear hereinafter, the novel combinations of elements being set forth in the appended claims.

Referring to the drawings, Figure 1 is a front elevation of an electric switch. or circuit-closer; Fig. 2 is .a rear elevation of the electro-magnet and its armature; Fig. 3 is a sectional side elevation showing the electro-magnet and armature in section, as well as the supporting board and part of the switch arm; Fig. 3 is afragmentary view showing a slight modification of the construction shown in Fig. 3. Fig. 4 is a sectional view of the spring buffer or vibration absorber; and Figs. 5, 6, 7 and 8 illustrate features of my invention in a different form.

The various parts of the electro-inagnetic switch are mounted on a board or base 1 of insulating material, preferably slate. A bracket 2 integral with the frame of the electro-magnet in this instance is secured to the base 1 by bolts 3. The body portion of the magnet comprises the laminations 4 of soft iron clamped together between the side members or plates 5, 5, of the magnet frame by means of bolts 6. I have shown the laminations 4 U-shaped and inverted, the horizontal portion being provided with a spool of -insulated Wire or a winding 70 adapted to \receive a single phase alternating current to energize the magnet.

A bracket 7 is secured to the front of the base 1 by means of bolts 8 which also secure in fixed position on the back of the board a bracket plate 9. Extending upwardly from the bracket 7 are arms 10, as indicated more clearlyin Fig. 1. The upper ends of these arms are provided with horizontally extending threaded holes in alinement with each other, and into these holes are fitted correspondingly threaded bolts 11 which are provided with conical inner ends 71, 71 to form cone bearings. The outer ends of the screws 11, 11 are provided with slots 72, 72 for the insertion of a screw-driver to enable the screws to be turned to adjust the position of the inner conical ends.

The armature A for the magnet is held between parallel arms 12, 12 united at one end preferably by an integral web 13 haw.- ing a vertical extension 14, the upper end of which is somewhat wider than the lower portion. This upper end is provided substantially in the central portions of its lateral faces with conical recesses for receiving the conical ends 71, 71 of the bolts 11, 11. After the latter have been moved inwardly so that their inner conical ends fit snugly, but not too tight, in the recesses of the extension 14, the nuts 16, 16 may be turned to lock the bolts 11, 11 to the arms 10, 10, and thus lock the conical ends 71, 71 in fixed position. Between the conical recesses in the extension 14 is a passage or hole 17 and communicating with the central portion of this passage is a vertical opening 18 screw-threaded to receive a threaded nut 19 which forms a (:10' sure for the opening. It will therefore be seen that passages are provided between the upper central portion of the extension 14 through the opening 18 and opening 17 to the bearing surfaces for the armature lever. This arrangement constitutes means for lubricat-ingt e armature lever bearings, the opening 18 being'filled with Vaseline or other suitable lubricant and forced through the passage 17 to the cone bearings by screwing down the nut 19.

The armature A comprises the soft iron laminations 20 which are clamped between the arms 12, 12 by means of a plurality of bolts 21. The weight of the armature is increased by a block of solid metal 22 which is secured between the arms 12 as by means of rivets 23.

The armature 20 is designed to have an approximately uniform pull exerted thereon by the electro-magnet throughout its range of movement. To accomplish this result the laminations of the armature are made a peculiar shape, such that a portion thereof moves between the poles 73, 7 1 of the electro-magnet and the end portions thereof are brought into proximity to the ends of sald pole when the armature is in its attracted position as shown in Fig. 3. The upper surface 75 of the laminations is inclined toward the pivot of the armature lever so as to be in a nearly radial plane with respect thereto. When the armature is in its initial position, therefore, the surface 75 will be nearly hori- Zontal and about in alinement with the lower surfaces of the poles 73 and 74. The end faces 76 and 77 of the portion of the armature movable between the magnet poles are inclined with respect to the vertical surfaces of the poles, so that the air gap between the surface 76 and the extreme lower end of the pole 73 remains substantially constant, whereas the air gap between the face 77 and the extreme lower end of the pole 7 1 gradually decreases. The end portions 78 and 79 of the laminations are initially at a com paratively long distance from the lower ends of the poles 73 and -74, respectively, but when the armature is brought to its raised position as shown in Fig. 3 the upper surfaces of these end portions are brought substantially parallel to the lower surfaces of the poles 73 and 74 and in close proximity thereto, but without touching them, except possibly when the armature is first attracted "and its inertia causes the portion 79 to strike a blow against the pole 74 which blow may be absorbed by the leather cushion 33. When the magnet is energized a large magnetic flux is at once produced through the armature, due to the central portion thereof being in close proximity to the poles of the magnet to decrease the air gap. As the central portion moves upwardly between the poles the pull on such central portion diminishes, but this is compensated for by the increased pull on theend portions 78 and 79 and on the lower portion of the face 77, until finally small air gaps are left. At nopoint do the armature laminations come in direct contact with the poles of the electro-magnet.

In order to absorb the vibrations due to the varying pull caused by the alternations of magnetism. and thus minimize chattering or humming noises when the armature is in its attracted position, I employ one or more spring buffer devices illustrated in Fig. 4. In Fig. 2 I have shown two of such buffer devices earried by lateral projections or arms 24, 24 extending from the plates 12 of the armature frame and located beneath similar projections or arms 25 on the magnet frame. Each butter comprises an externally screwthrcadcd tube 28 which is adjustable vertically in the threaded opening 27 in the arm 24 and may be locked in its adjusted position by a nut 28. The internal diameter of the tube is larger along its upper portion in this instance than along the lower pol tion. A comparatively very strong, stiff and unyielding helical spring extends through the length of the tube 26 and projects a short distance above the upper end of the tube. This spring is securely fastened in the tube 26 by any suitable means so as to be as rigid as possible with the arm 24. In this instance I have shown a metal plug 30 of suflicient diameter to require some force to put it in proper position so that the lower portion of the spring 29 will be held very tightly against the tube 26. Preferably the spring 29 is made of steel. having consider able resiliency and elasticity, extra hard and very strong, so that it can hardly be compressed to a perceptible degree by hand and yet when placed in position to absorb vibrations of an armature of an alternating current magnet it will almost entirely eliminate chattering or humming noises. The plug 30, the tube 26 and the nut 28 may be made of iron, and so also the arm 24, so that the magnetic air gap will be closed by the spring 29 to some extent at least when the magnet attracts the armature to the position shown in Fig. 3 where the armature is almost in magnetic equilibrium, and the only air gap is that between the pole 74- and the faces 77 and 80. It should be understood, however, that the plates 12, 12 and the buffer holders 24, 24 are usually made of brass or non-magnetic material, so that the only portions composed of iron are the laminations 20, and usually also the weight 22. In any event. however, the arrangement is such that the pull exerted on the armature produces a. substantially uniform movement of the latter and is held in attracted position with slightly, if any, greater force than at the beginning of its movement. The armature when in attracted position is nearly equilibrated magnetically, so that the tendency for vibration is greatly minimized and the amplitude of such vibration as does occur is reduced by the strong, elastic buffer springs 29, 29. It should also be understood that the position of the spring on the armature lever may be varied, or it may be placed on a fixed part instead of on a movable art.

Fig. 3 shows a modification in which the poles 73 and 74: of the magnet have their inner faces curved so as to leave a wider space between these faces and the faces 76 and 77 of the arm. As a result, some of the magnetic lines forced will pass through the horizontal air gaps, thus greatly reducing the magnetic pull at the surfaces 76 and 77, and increasing the vertical magnetic pull on the armature.

The use of a spring in an alternating current magnet switch for-the purpose of absorbini" the vibrations is old in the art, as shown for example in the Patent No. 791,591

granted June 6, 1905, and the Patent No. 792,859 granted June 20, 1905, both.to D. L. Lindquist and myself as joint inventors, and in the patent to Lindquist No. 863,296 granted August 13, 1907. But the present invention is an improvement on such devices in the use of springs that are substantially non-compressible under the attraction exerted. The springs used heretofore have not eliminated the chatteri or humming due to alternations of magnetism, but it has been found in practice that by the use of a very strong, stifl' iron spring having a high temper and being very resilient to impact and elastic to pressures capable of compressing the same, that the noise, hum or chatter of an alternating current magnet holding an armature in its attracted position is substantially eliminated, so that the vibratory noise is scarcely perceptible when a few feet away. The arrangement of such a sprin held tightly in position is an important eature of my invention, as it is a distinct step in the advancement of the art, that is, an important improvement over springs heretofore employed for similar purposes.

A back-stop 35 for the armature lever is adjustably mounted on a bracket 9 by means of a bolt 36 screw-threaded for adjustment inthe lug 37 formed on the bracket 9. The upper end of the bolt 36 may consist of a smooth cylindrical portion 38 extending into and movable in a correspondingly shaped opening or recess in the stop 35. A look nut 39 serves to lock the bolt 36 in its adjusted position. The stop 35 has a face 40 of leather, rubber or light material.

The switch lever S is pivoted near its lower end on a horizontal rod 41 which is supported at its ends in outwardly extending lugs or brackets 42, 42 formed on the lower portions of the arms 10, 10. This lever comprises two arms 43, 43 extending upwardly from the hub portion of the lever, which arms are connected intermediate their end-s by a cross-piece 44. Each of these arms carries at its upper end a contact 45 having a stem 46 extending through the arm and insulated therefrom by the bushing 47. The stem 46 is screw-threaded to receive the clamping nuts 48 which serve to clamp the contact 45 in osition and also mechanically and electrical y unite the connector 49 with said contact. Connectors 49, 49 form the upper terminals of flexible conductors 50, 50, the lower ends of which are provided with binding posts 51, 51 which extend through the base-board 1 and are provided with clamping nuts 52. Connectors 53 on the ends of the conductors leading to the switch board are clamped between the locking nuts 52.

Carbon contacts 53 are held by clamps 54 of ordinary construction. In this instance I have shown each clamp carried by a rod or stem 55 which extends through a sleeve 56. This sleeve extends through the ba se-board 1 and is held in positlon by a flange 57 on the front and lock nuts 58 on the back of the board, these lock nuts bein screw-threaded on the sleeve 56. Within tie sleeve 56 is a coil spring 59 surrounding a portion of the stem 55 reduced in diameter and operating to yieldingly hold the contact 53 in its outer position. The rear end of the stem 55 is screw-threaded to receive the nut 60, by means of which the tension of the spring may be adjusted. The stem 55 also serves as a binding post for the connector 61 which is clamped in position by the nuts 62.

The switch lever S is held in its closed position by a coil spring 63. The forward end of this spring bears against an arm 64 extending downwardly from the hub of the switch lever and is held in such position by a lug 65formed on the lover. The rear end of the spring extends through an opening 66 in the bracket 7 and base 1 and bears against the inner face of the bradret 9, being held in position by a nose 67 formed on the bracket 9. A roller 68 is journaled between the arms 43 a short distance above the pivot of the switch lever and in the'path of movement of the extension 14 of the armature lever. When the armature is in its attracted position, as shown in Fig. 3, and the spring 63 holds the contacts 45 and 53 in engagement with each other, the roller 68 occupies such a position that it is spaced a short distance from the extension 14, so that no vibrations of the armature lever may be transmitted to the switch lever S. The electric switch is therefore held closed by the spring 63 independently entirely of any illterations of magnetism.

lVhen the magnet is de'e'nergized the weight of the armature lever, particularly at its outer end, exerts sufficient force on the extension 14 to cause the latter to abut against the roller 68 and compress the spring 63 and move the switch to open position. In other words, the weight of the armature is suflicient to effect the opening of the switch against the action of the s ring 63 when the electro-magnet releases tie arma ture and the latter swings downwardly. \Vhen the magnet is again energized the armature is lifted by the magnetic pull, aided by the spring 63 acting through the switch lever.

The stop 35 is so located that the armature when in its lower position is well within the influence of the magnet, and the shape of the armature is such that the face is in an approximately horizontal positi0n,with its end edges in close proximity to the inner lower edges of the magnet poles 73 and 74 so that the air gap between the magnet and the armature even at this time is very small. As a result of this arrangement there is a large magnetic flux throu h the armature when a current is sent t rough the coil 70, which not only secures a strong pull on the armature but produces sufiicient self-induction, due to the magnetic circuit being almost closed, to prevent the heavy inrush of current through the winding which otherwise occurs before the armature is brought to attracted position. The armature is so designed, therefore, that the magnetic air gap is always very small, and yet sutficient pull is constantly exerted on the armature to move it to its attracted position, where it will remain in a position of approximate equilibrium so that there will be minimum tendency for the alternations of magnetism to cause vibrations. The stop 35 is adjustable up and down to hold the armature initially in the position found to give the best results in practice, and which may vary with the strength of current used, and other variable factors. It will therefore be seen that initially a magnetic pull is exerted on the cehtral portion of the armature to move the same upwardly. The spring 63 also tends to move the armature in the same direction until the electric switch is closed. As the faces 76 and 77 move between the pole pieces, the upward pull on the armature decreases. since the flux then passes laterally and has no effect in moving the armature. This is particularly true if the faces 76, 77 and the inner faces of the poles are struck as arcs with the pivot of the armature lever as a center. In such event the end faces of the portion 20 and the inner faces of the poles will be parallel, and continued movement of the armature must depend on the end portions 78, 79 and the lower part of the inner portion :20 approaching the poles In this instance the face 77 is designed to approach nearer and nearer the pole 74 at the same time that the ends 78, 79 approach the pole faces. Therefore as the pull on one portion of the armature decreases, it in creases proportionately on another portion, with the result that a substantially uniform pull is obtained throughout therange of movement of the armature, and the latter may be held in attracted position against the stiff hufl'er springs firmly and yet the armature is in such a field as to. be magnetically equilibrate; that is to say, the armature in its attracted position so completely closes the magnetic circuit that the tendency for any further movement is reduced to a mini mum. In other words, the armature tends to float in the position where the armature lever abuts against the buffer springs, there being still sufficient pull to resist downward movement, and yet not tending to move the same upwardly with any material force against the buffer springs.

Figs. 5, 6, 7 and 8 illustrate a modifica- The magnet bracket 2 is secured to the baseboard I by the bolts 3, 3'. To the central portion of this bracket are secured the laminations 4' to form an interior pole of the magnet as indicated in Fig. 7. The sole noid is removably held in position by the strip 99 extending through the solenoid from the laminations 4. The lower portion of the bracket 2 is bifurcated to form the arms 10', 10 which carry the conical bearings 71, 71', between which is pivoted the armature lever 14. This armature lever carries the laminated armature A projecting into the solenoid as indicated in Fig. 7, and being of sufficient size to prevent the removal of the solenoid 70 over the strip 99 when the armature lever is in proper position. It will be noticed that the laminations 4 and A are arranged horizontally and that the bearings 71, 71 are adjustable laterally by means of the bolts 11, 11. By this arrangement the air gap 100, as shown in Fig. 7, may be made symmetrical and thus further reduce the tendency of the inagnet to hum. Extending upwardly from the bracket 2' is an arm 81 through which extends the rod 43 carrying at one end the contact 45 and at its other end the adjustable nuts 68. A conical spring 63 located in a recess 66 urges the contact 45 into engagement with the fixed contact 53. When the magnet is deenergized, however, the upper extension 83 of the armature lever abuts against the nut 68 and holds the contact 45 and the rod 43 in the position shown by the dot-and-dash lines. By having the spring conical, the magnet as a whole may be placed near the board 1. It will be seen that the opening 82 in the extension 83 is of larger diameter than the rod 43', so that when the magnet is energized to hold the armature in its full line position the spring (33 holds the contact 45' against the fixed contact 53' independently of any movable portion of the armature lever. When the magnet is denergized and falls to the position shown by the dot-and-dash lines, the extension 83 causes the disengagement of the contacts 4 5 and 53'. By a comparison with Fig. 3 it will be evident that the opera tion of the construction there shown is very similar, in that when the armature is moved to its attracted position to release the switch lever the spring 63 automatically closes and holds closed the electric switch independently of the armature lever. It should be noted that the upper arm 81 is rigid with the bracket 2 which is fixed to the board 1. On the opposite side of the recess 66 is the cylindrical projection or holder 85, in a slot 101 of which is securely wedged one end of the spring 29 to hold it firmly in proper posit m to absorb the vibrations of the armature lever, the extension 83 abutting tion embodying principles of my inventions; against the same as indicated in Fig. 5. This other terminal of the transformer.

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spring is of similar construction as the spring 29 shown in Fig. 4, and is so located as to prevent the armature lever from being moved inwardly to such an extent that the laminations 4 and A will come into contact with each other. Preferably the bracket 2 and the arm 81, extensions 10, the bearings 71, the armature lever 14, the arm 83, and the spring 29 are made of magnetic material, such as iron, so as to assist in closing the magnetic circuit of the electro-magnet and thus increase its efficiency by reducing the current consumption.

In Fig. 5 the armature lever itself is ,of

suflicient weight to open the electric switch against the action of the comparatively light sprin 63. The outward movement ofthe arm is limited, however, by the contact 81 striking against the back-stop 35'. The contact 81 is mounted on the end of the rod 80 which is fastened to the armature lever. If desired, a circuit may be closed by the engagement of the contact 81 with the backstop 35 when the magnet is deenergized. To illustrate an application of the electric switch I have shown a transformer 88 having leads 86 and 87 which may be connected to any suitable source of alternating current supply. When the primary of the transformer 88 is being supplied with current and the switch 89 is closed, the electro-magnet may be energized by closing the switch 93. A circuit may then be traced through the conductors 90, 91, solenoid conductor 92, switch 93, conductor 94, to ltiie e magnet solenoid 70' upon receivin current will move the 'arm 83 against t e bufl'er spring 29 and release the rod 43 so that the spring 63 can move the contact 45' into engagement with the'fixed contact 53. A circuit may thenbe traced through the conductor 90, translating devices 96, conductor 97, rod or stem 43', contacts 45, 53', contact stem 55', conductor 98, to the other terminal of the secondary of the transformer 88.

I have shown and described constructions embodying my invention in forms which have been found to bevery practicable in operation and highly efiicient, but I do not wish to be limited to the precise construction disclosed, as various changes in the details of construction and arrangement of partsmight obviously be made by those skilled in the art without departing from the spirit and scope of my invention.

Having thus fully described my invention, what I claim and desire to have protected by Letters Patent of the United States is 1. In an electro-magnet-ic switch, the combination with an electro-magnet, of an armature therefor, a fixed bracket. a screwthreaded bolt in the bracket, and a sto for the armature slidable on the bracket and connected to said bolt and adjustable thereby.

2. The co1nbination, ,vyith a support, of a magnet and its armature, a bracket secured to said support, a screw-threaded bolt adj ustably connected to the bracket, and a stop slidably held by said bolt on the bracket.

3;. The combination with a support and and having an outwardly extending lug, tl vertical screw threaded bolt extending through the threaded opening in the lug and vertically adjustable therein, a lock nut on the bolt, a cylindrical extension on the upper end of the bolt, an armature stop or bumper recessed to receive said extension and having a flat vertical surface bearing against and slidable on the vertical face of the bracket and a contact surface in the path of the armature, and a facing of soft material on said contact surface.

5. The combination with an electro-magnet and its armature, of a sleeve carried by one of said parts, a spring connected to the sleeve and forming a stop for the armature, and means for ad usting the sleeve.

6. The combination with an electro-mag net and its armature, of an externally screwthreaded sleeve adjustable in one of said parts, and a spring secured in the sleeve and positioned to form a stop for the armature.

7. The combination with an electro-magnet and its armature, of a lug extending from the armature and formed with a screwthreaded opening therethrough, an externally threaded sleeve adjustable in said opening, means for locking the slew-re in adjusted position, and a coil spring mmnected to said sleeve.

8. The combination with an elecro-magnet and its armature, of lugs extent'ling laterally from the magnet, similar lugs extending laterally from the armature, said last named lu having openings theretlireugh, sleeves ad ustable in said openings. and coil springs carried by said sleeves and projecting beyond the ends of the same. 7

9. In an armature for an electro-magnet, the combination with a frame comprising parallel plates, of an integral web uniting the plates, iron laminations between the said plates, bolts for clamping said plates and laminations rigidly together, and a. solid block of metal located beneath and spaced from the iron laminations.

10. In an armature for an electro-magnet, the combination with a pair of parallel anelectro-magnet and its armature, of a a plates, an integral web uniting the plates at one end, and iron laminations between the said plates.

11. in an electromagnet provided with an armature, a coil spring to take up vibrations of the armature, a tubular member securing the spring rigidly to one of said parts and means for adjusting said tubular member to vary the tension of the spring.

12. In an electromagnet provided with an armature subject to vibrations due to cur rent vibrations, a spring buffer connected to one of said parts and comprising a tubular member having internal cylindrical surfaces of different diameters, a helical spring, and

means for rigidly securing a portion of said spring to the surface of smaller diameter.

13. In an clectromagnet provided with an armature subject to vibrations, a spring buffer to take up the vibrations and comrising a sleeve, a coil spring extending within the sleeve and a plug within the spring and securing it rigidly to the sleeve. In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

AUGUST SUNDH. \Vitnesses:

CHAS. M. NISSEN, ALFRED C. Bncnn'r. 

